What is the recommended immediate management for a patient presenting with acute ST‑elevation myocardial infarction (STEMI)?

Immediate Management of STEMI

Primary percutaneous coronary intervention (PCI) performed within 90-120 minutes of first medical contact is the definitive reperfusion strategy for STEMI, with immediate aspirin and potent P2Y12 inhibitor administration, anticoagulation, and direct transfer to the catheterization laboratory bypassing the emergency department. 1

Initial Assessment and Diagnosis

• ECG confirmation must occur at first medical contact, whether in the ambulance or hospital, to establish STEMI diagnosis with persistent ST-segment elevation 1
• Pre-hospital ECG with tele-transmission to experienced cardiologists enables immediate activation of the catheterization laboratory and reduces time to reperfusion 2
• Assess for contraindications to reperfusion therapy including active internal bleeding, recent cerebrovascular accident, intracranial pathology, and severe uncontrolled hypertension 3

Reperfusion Strategy: Time-Critical Decision

Primary PCI (Preferred Strategy)

If primary PCI can be performed within 120 minutes of STEMI diagnosis by an experienced team, this is the mandatory approach 1, 4:

• Transfer patient directly to the catheterization laboratory, bypassing emergency department and CCU/ICCU 1
• The 90-120 minute window is measured from first medical contact, not hospital arrival 1, 4
• Primary PCI remains indicated for all patients with symptoms ≤12 hours duration 1, 4
• Even with expected delays, primary PCI is superior to fibrinolysis when performed within 120 minutes 5

Fibrinolytic Therapy (When PCI Cannot Be Timely)

If primary PCI cannot be performed within 120 minutes, administer fibrinolytic therapy immediately, preferably in the pre-hospital setting 1, 4:

• Use fibrin-specific agents: tenecteplase (preferred), alteplase, or reteplase 1
• Tenecteplase dosing is weight-based: <60 kg = 30 mg, 60-70 kg = 35 mg, 70-80 kg = 40 mg, 80-90 kg = 45 mg, ≥90 kg = 50 mg, administered as single IV bolus over 5 seconds 3
• Greatest mortality benefit occurs within first 3 hours of symptom onset (35 lives saved per 1000 patients vs. 16 lives saved per 1000 at 7-12 hours) 4
• All patients receiving fibrinolysis must be transferred to PCI-capable center immediately after administration 1

Immediate Pharmacotherapy

Antiplatelet Therapy

• Aspirin 160-325 mg orally (or IV if unable to swallow) immediately upon STEMI diagnosis 1, 4
• Potent P2Y12 inhibitor before or at time of PCI: prasugrel or ticagrelor preferred over clopidogrel 1, 6
• Continue dual antiplatelet therapy for 12 months unless excessive bleeding risk 1

Anticoagulation

For Primary PCI 1:

• Unfractionated heparin as weight-adjusted IV bolus followed by infusion
• Fondaparinux is contraindicated for primary PCI 1

For Fibrinolytic Therapy 1:

• Enoxaparin IV followed by subcutaneous (preferred over unfractionated heparin)
• Continue until revascularization or hospital discharge (up to 8 days)

Pain Management

• Morphine sulfate 4-8 mg IV with additional 2 mg doses at 5-15 minute intervals for pain control and anxiety reduction 7
• Morphine reduces sympathetic drive and myocardial oxygen demand 7
• Avoid nitrates if patient has taken phosphodiesterase-5 inhibitors (contraindicated for 48 hours after tadalafil due to risk of fatal hypotension) 6

Additional Immediate Therapies

• High-intensity statin therapy initiated immediately in all STEMI patients 6
• Beta-blockers (metoprolol): In hemodynamically stable patients, consider IV metoprolol 5 mg every 2 minutes for three doses, followed by oral therapy 8

Post-Fibrinolysis Management Strategy

Critical timing windows for angiography after fibrinolysis 1:

• Rescue PCI immediately if fibrinolysis fails (<50% ST-segment resolution at 60-90 minutes) or hemodynamic/electrical instability develops 1
• Emergency angiography for heart failure/shock regardless of fibrinolysis success 1
• Routine angiography 2-24 hours after successful fibrinolysis in stable patients 1
• Emergency angiography for recurrent ischemia or reocclusion evidence 1

Critical Pitfalls to Avoid

• Never delay reperfusion for routine laboratory tests or imaging beyond ECG 5
• Do not administer nitrates without confirming no recent phosphodiesterase-5 inhibitor use 6
• Avoid benzodiazepines as they cause respiratory depression, hypotension, and may obscure clinical signs of complications 7
• Do not use fondaparinux for primary PCI (only for fibrinolytic strategy) 1
• Flush dextrose-containing IV lines with normal saline before tenecteplase administration to prevent precipitation 3
• Do not perform routine PCI of occluded infarct-related artery >48 hours after symptom onset in asymptomatic stable patients 1

Monitoring and Assessment

• Continuous cardiac monitoring for arrhythmias and hemodynamic instability throughout acute phase 7
• Routine echocardiography during hospital stay to assess LV/RV function, detect mechanical complications, and exclude LV thrombus 1, 6
• Monitor for bleeding complications, particularly intracranial hemorrhage with fibrinolytic therapy 3

Special Populations

• Cardiogenic shock/heart failure: Emergency angiography and PCI indicated regardless of time from symptom onset 1, 4
• Symptoms 12-24 hours: Reperfusion (preferably primary PCI) indicated if evidence of ongoing ischemia 4
• Beyond 24 hours: Routine PCI not recommended in stable patients without ischemia 4